Self-Driven and Blue-Enhanced Photodetectors Based on Organic/Inorganic Heterojunction of Pentacene and Bi₂Se₃

Nanoscale-thick organic/inorganic hybrid heterojunction functioning as the core optical active layer of a photodetector has many significant advantages due to its enhanced light absorption, excellent interface quality, higher mechanical stability, and intralayer excitonic dynamics. However, via controlled growth of high-quality 2D pentacene/Bi 2 Se 3 heterojunction to further improve the performance metrics of photodetectors has rarely been investigated. Therefore, to further explore its utilization potentiality in optoelectronics, the newly conceived organic/inorganic heterojunctions with sharp interface were controllably grown based on small-molecule pentacene and topological insulator Bi 2 Se 3 nanometer films. Then, a self-driven and blue-sensitive heterojunction photodetector was fabricated. Note that the photodetector with nanoscale thickness exhibits a reversible photocurrent switching performance with higher photoresponsivity of 4.834 A/W and detectivity of 1.62 × 10 10 Jones under 405 nm blue-light irradiation. Through integrating several surface-sensitive characterization techniques, the robust interface Schottky potential was experimentally revealed, which was derived from the metallic and few nanometers thick Dirac surface state of the Bi 2 Se 3 crystal. This contact behavior is beneficial to improve the separation capability of electron–hole pairs and promotes the photoelectric conversion efficiency of the heterojunction. This study provides an in-depth understanding of the basic photophysics of pentacene/Bi 2 Se 3 heterojunctions, and the newly designed photodetector has broad application prospects in low-power and flexible optoelectronics.